The death toll from a devastating earthquake off the coast of Haiti may reach the thousands, aid workers said Wednesday after viewing extensive damage in the capital of Port-au-Prince.

The situation in Haiti is “truly heart wrenching” in a nation that is “no stranger to hardship and suffering,” President Obama said at a press conference Wednesday. He promised a “swift and aggressive” effort including rescue workers and humanitarian aid as part of a coordinated international response.

In Geneva, a spokesman for the International Committee of the Red Cross (ICRC) estimated that as many as 3 million people in the impoverished country may have been affected by the quake, according to the Associated Press. The ICRC predicted that it would take 24 to 48 hours for a clear picture to emerge of the scale of the destruction.

According to the UN, the island is the scene of widespread devestation. Collapsed buildings include the national penitentiary, where prisoners have escaped, the National Palace (President Rene Garcia Preval is said to be safe), the Parliament Building, the National Cathedral and at least four other ministry buildings including the finance ministry.

The main airport’s control tower is said to have collapsed, hindering rescue efforts. But the airport is said to be operational, and planes carrying aid from the UN are expected to arrive in Port-au-Prince this morning. A UN spokesperson in Geneva says the road from the airport is badly damaged.